reproduced with Inkscape 0.47 r22583 (gtk2 2.16.6 ?) and 0.47+devel r9081 (gtk2 2.18.6, gtkmm 2.18.2) on OS X 10.5.8
this happens with other dialogs as well (e.g. with Inkscape 0.47+devel the 'Document Properties' dialog after expanding 'Resize page to content...' does not shrink back to the original dialog window size)
reproduced with Inkscape 0.47 r22583 (gtk2 2.16.6 ?) and 0.47+devel r9081 (gtk2 2.18.6, gtkmm 2.18.2) on OS X 10.5.8
this happens with other dialogs as well (e.g. with Inkscape 0.47+devel the 'Document Properties' dialog after expanding 'Resize page to content...' does not shrink back to the original dialog window size)